This application is related to U.S. Pat. No. 5,909,278, issued Jun. 1, 1999, which is incorporated in its entirety by this reference.
As shown in FIG. 1, the traditional multi-source excitation detection system is a fixed, inflexible design that uses four Photo-Multiplier Tubes (PMT) to detect a maximum of four fluors, resulting in one fluor detected per PMT. A fluor is a small molecule, or a part of a larger molecule, which absorbs light and, in the case of a fluorophore, emits light through fluorescence. Dyes containing fluors with similar emission spectra can be used together if they are excited by different lasers. The excitation sources and detectors are typically spaced 200 microns apart, and the excitation sources are permanently assigned to be a 488 nm laser or a 633 nm laser.
As shown in FIG. 2, other traditional multi-source excitation detection systems, which have a slightly more flexible design, use four Photo-Multiplier Tubes (PMT) to detect a maximum of four Fluors, still resulting in one Fluor detected per PMT. This system features coincident lasers and detectors, where the detectors are permanently assigned to both 488 nm and 633 nm laser beams, but cannot distinguish between the results of them. Dyes with similar emission spectra cannot be used together, even if the dyes are excited by different lasers. The system shown in FIG. 2 features improved flexibility over the system shown in FIG. 1, but the detection is limited to four non-overlapping fluorophores.
With the traditional systems shown in FIGS. 1-2, adding additional analytical capability (the ability to detect additional colors) requires addition of detectors, which increases cost, complexity, and size. Presently in the art, a single detector system cannot distinguish between two or more fluorphores when excited by two or more excitation sources and when having overlapping fluoresecence.
Thus, there is a need in the flow cytometer field to create a new and useful multi-source excitation detection system. This invention provides such new and useful multi-source excitation detection system.